Answer:
In Exodus 24 we read of Moses sprinkling blood as an important part of a ceremony commanded by God. The context shares part of the reason for this ritual:

[Moses] got up early the next morning and built an altar at the foot of the mountain and set up twelve stone pillars representing the twelve tribes of Israel. Then he sent young Israelite men, and they offered burnt offerings and sacrificed young bulls as fellowship offerings to the Lord. Moses took half of the blood and put it in bowls, and the other half he splashed against the altar. Then he took the Book of the Covenant and read it to the people. They responded, “We will do everything the Lord has said; we will obey.”

Moses then took the blood, sprinkled it on the people and said, “This is the blood of the covenant that the Lord has made with you in accordance with all these words.” (verses 4–8)

The twelve stone pillars represented the twelve tribes of Israel. Animal sacrifices were made to the Lord, with half the blood thrown on the altar and half kept in bowls. Moses then read the Book of the Covenant to the people, and the people pledged their obedience.

After these actions, Moses sprinkled the blood from the bowls on or toward the congregation of people. This blood represented the sealing of a covenant or promise to the people of Israel. Because blood represents life (see Leviticus 17:14), its sprinkling on the congregation represented a vital commitment between God and His people.

This act would have connected with other uses of blood in Scripture as well. Abraham, the father of the people of Israel, used animal sacrifice. He also was the first to begin the covenant of circumcision, which was used as a sign of the covenant with the Lord (Genesis 15:11).

In the New Testament, Jesus Christ spoke of blood during the Last Supper. In sharing a final meal with His followers, He said the wine represented His blood that would be poured out for us (Luke 22:20). His blood was the seal of the new covenant of grace (1 Corinthians 11:25). His death on the cross was the perfect sacrifice on behalf of the sins of humanity and served as a fulfillment of the ritual sacrifices of the Old Testament.

Today, Christians no longer offer animal sacrifices involving blood, but instead have atonement through faith in Jesus Christ. He is the way, the truth, and the life (John 14:6) and the only way to God (Acts 4:12). Through faith in Jesus Christ, any person who believes in Him can have everlasting life (John 3:16). “Jesus [is] the mediator of a new covenant, and . . . the sprinkled blood” (Hebrews 12:24).